// Package cli implements the vellum command-line subcommands that operate
// directly on the database: user administration and backups.
//
// cmd/vellum calls Run before booting the HTTP server. When Run reports
// handled == true the process exits without starting the server; when it
// reports handled == false the caller falls through to its default behaviour.
package cli

import (
	"context"
	"database/sql"
	"errors"
	"fmt"
	"io"
	"log/slog"
	"os"

	"github.com/mithral/vellum/internal/auth"
	"github.com/mithral/vellum/internal/core"
	"github.com/mithral/vellum/migrations"
)

// Run dispatches a CLI subcommand. args is os.Args[1:].
//
// handled is false when args names no known subcommand, so the caller can
// continue with its normal startup. When handled is true the database has been
// opened and migrated, and a non-nil error is fatal to the invocation.
func Run(args []string, cfg core.Config, log *slog.Logger) (handled bool, err error) {
	return run(context.Background(), args, cfg, log, os.Stdout)
}

// run is the testable core of Run. It opens and migrates the database only
// once a subcommand has actually been matched, so an unrecognised argument
// leaves the database untouched.
func run(ctx context.Context, args []string, cfg core.Config, log *slog.Logger, out io.Writer) (bool, error) {
	if len(args) == 0 {
		return false, nil
	}
	switch args[0] {
	case "user", "backup":
	default:
		return false, nil
	}

	db, err := core.OpenDB(cfg.DBPath)
	if err != nil {
		return true, err
	}
	defer db.Close()

	if err := core.Migrate(ctx, db, migrations.FS, log); err != nil {
		return true, err
	}

	switch args[0] {
	case "user":
		return true, userCmd(ctx, db, args[1:], out)
	case "backup":
		return true, backupCmd(ctx, db, args[1:], out)
	}
	return false, nil
}

// ── user ───────────────────────────────────────────────────────────────

func userCmd(ctx context.Context, db *sql.DB, args []string, out io.Writer) error {
	if len(args) == 0 {
		return errors.New("user: missing subcommand (add, passwd, list)")
	}
	switch args[0] {
	case "add":
		return userAdd(ctx, db, args[1:], out)
	case "passwd":
		return userPasswd(ctx, db, args[1:], out)
	case "list":
		return userList(ctx, db, out)
	default:
		return fmt.Errorf("user: unknown subcommand %q", args[0])
	}
}

func userAdd(ctx context.Context, db *sql.DB, args []string, out io.Writer) error {
	admin := false
	var positional []string
	for _, a := range args {
		if a == "--admin" {
			admin = true
			continue
		}
		positional = append(positional, a)
	}
	if len(positional) != 2 {
		return errors.New("usage: user add <username> <password> [--admin]")
	}

	u, err := auth.CreateUser(ctx, db, positional[0], "", positional[1], admin)
	if err != nil {
		return err
	}
	_, err = fmt.Fprintf(out, "created user %d %s\n", u.ID, u.Username)
	return err
}

func userPasswd(ctx context.Context, db *sql.DB, args []string, out io.Writer) error {
	if len(args) != 2 {
		return errors.New("usage: user passwd <username> <newpassword>")
	}
	username, password := args[0], args[1]

	u, err := auth.GetUserByUsername(ctx, db, username)
	if errors.Is(err, sql.ErrNoRows) {
		return fmt.Errorf("user %q not found", username)
	}
	if err != nil {
		return err
	}
	if err := auth.SetPassword(ctx, db, u.ID, password); err != nil {
		return err
	}
	_, err = fmt.Fprintf(out, "updated password for user %d %s\n", u.ID, u.Username)
	return err
}

func userList(ctx context.Context, db *sql.DB, out io.Writer) error {
	users, err := auth.ListUsers(ctx, db)
	if err != nil {
		return err
	}
	for _, u := range users {
		if _, err := fmt.Fprintf(out, "%d\t%s\tadmin=%t\n", u.ID, u.Username, u.IsAdmin); err != nil {
			return err
		}
	}
	return nil
}

// ── backup ─────────────────────────────────────────────────────────────

func backupCmd(ctx context.Context, db *sql.DB, args []string, out io.Writer) error {
	if len(args) != 1 {
		return errors.New("usage: backup <path>")
	}
	path := args[0]
	if _, err := db.ExecContext(ctx, "VACUUM INTO ?", path); err != nil {
		return fmt.Errorf("backup: %w", err)
	}
	_, err := fmt.Fprintf(out, "backed up database to %s\n", path)
	return err
}